Interlocking mechanism for electrical controllers



Feb. 18,1969 F. DRE-IE5 ET AL 3,428,764

IN TERLOCKING MECHANISM FOR ELECTRICAL CONTROLLERS Feb. 18, 1969 J. F. DREES ET AL 3,428,764

INTERLOCKING MECHANISM FOR ELECTRICAL CONTROLLERS Filed April 3, 1967 Sheet 2 of 5 1s comers c0NTACTs OPEN OPEN 4 J75 com/ms I CLOSED o??? J- F. DREES ET AL I Feb. 18, 1969 INTERLOCKING MECHANISM FOR ELECTRICAL CONTROLLERS Filed April 5, 1967 United States Patent Claims ABSTRACT OF THE DISCLOSURE An interlocking mechanism for three electromagnetically operated contactors, each of which has an open and closed position. The interlock comprises a lever for preventing the simultaneous closure of the first two of the contactors and further comprises a single connecting rod and multiple lever system for preventing closure of the third contactor while either of the first two contactors are closed and preventing closure of either of the first two contactors while the third contactor is closed.

Back ground 07 the invention This invention relates to mechanical interlocks for electrical devices and more particular-1y for mechanical interlocks for motor controllers including forward, reverse and dynamic braking contactors.

Prior to the present invention there existed a variety of mechanisms for performing interlocking functions similar to that of the mechanism herein disclosed. However, because of the multiple interlocking functions involved in a. controller such as is herein disclosed, the previous mechanisms tended to be complex and might consist of several separate linkage and lever systems. The present device improves on the prior art in combining'the several interlocking functions into a single easily adjusted mechanical lever and linkage system of minimum complexity.

Summary It is an object of the invention to provide a more simple and reliable mechanical interlock system for electrical controllers which include multiple electrical contactors.

It is a more specific object of the invention of the aforedescribed type for an electric motor controller comprising forward, reverse and dynamic braking contactors which are mounted adjacently within the controller cabinet.

The objects of the invention are accomplished by providing first mechanical interlocking means between first and second contactors to prevent simultaneous closure of these contactors and further coupling the first interlocking means to a second interlocking means associated with a third contactor. The second interlocking means comprises a multiple member system arranged so that a first member is moved into position to block the closure of the third contactor when the first contactor is closed. Another member moved to block closure of the third confactor when the second contactor is closed. The second interlocking means is further arranged so that when the third contactor is closed, movement of the two members is blocked. The second interlocking means is also coupled to the first interlocking means to consequently prevent closure of either of the first two contactors.

Brief description of the drawings FIGURE 1 is a front elevational view of an interlocked electrical controller with the doors thereof partially broken away which incorporates the present invention;

3,428,764 Patented Feb. 18, 1969 "ice FIG. 2 is a fragmentary view of the device shown in FIG. 1 showing the mechanism in a second position;

FIG. 3 is a fragmentary view similar to FIG. 2, but with the mechanism in a third position;

FIG. 4 is a fragmentary view showing a portion of the mechanism of FIGS. 1, 2 and 3;

FIG. 5 is a side view of the portion shown in FIG. 4; and

FIG. 6 is an isometric partially exploded view of the mechanical portion shown in FIGS. 4 and 5.

Description of the preferred iembodiment A motor controller assembly is illustrated in FIG. 1 consisting of an enclosure 2 with front doors 3 and three electromagnetically operated contactors 4, 5 and 6 mounted in compartments of enclosure 2. Contactors 4, 5 and 6 can be of various commonly available types of medium voltage electromagnetically operated controllers, each having open and closed contact positions. Contactors 4, 5 and 6 have projections 7, 8 and 9, respectively, extending therefrom which are attached to the operating mechanisms thereof. Projections 7, 8 and 9 move vertically between positions corresponding to the open and closed positions of the associated contacts. As preferably illustrated, projections 7, 8 and 9 are in their open positions when in their lower positions and are in their closed positions when in their upper positions.

The arrangement shown in FIG. 1 is typical of a motor controller for forward, reverse and dynamic braking control. Contactor 4 is the reverse contactor which when closed causes a motor (not shown) to run in a reverse direction. Contactor 5 is the forward contactor which when closed causes the motor to run in a forward direction. Contactor 6 is a dynamic braking contactor which when closed causes dynamic braking of the motor.

As is well known, it is necessary to prevent the forward contactor 5 and the reverse contactor 4 from being closed at the same time. For this purpose there is provided a rocking lever interlock or teeter bar 10. Lever 10 is pivotally mounted at its center on a pin 11 which is supported by a steel bracket assembly 12. Bracket 12 is rigidly secured to a bottom surface 13 of enclosure 2. At opposite ends of lever 10 there are similar depending rounded protuberances 14 and 15 which are positioned to contact projections 7 and 8, respectively, during operation. FIG. 2 shows both the forward contactor 5 and the reverse contactor 4 in their open positions. Projections 7 and 8 are in their lower positions spaced from protuberances 14 and 15 on lever 10. From this position either one or the other of contactors 4 or 5 may be activated to a closed position as shown in FIG. 3 and FIG. 1, respectively. However, both may not be closed simultaneously because if contactor 4 is closed as shown in FIG. 3, projection 7 rises to raise the left end of lever 10. The right end of lever 10 consequently lowers and protuberance 15 holds projection 8 down to prevent closure of contactor 5. Similarly, as shown in FIG. 1, if contactor 5 is closed, projection 8 tilts lever 10 to the left and contactor 4 is held open by the engagement of protuberance 14 with projection 7.

As is also well known in the field of motor control, the dynamic braking contactor must not close if either one of contactors 4 and 5 is closed, and neither one of contactors 4 and 5 may be allowed to close if the dynamic braking contactor 6 is closed. For these purposes another interlocking mechanism is provided to cooperate with projection 9 on contactor 6.

The linkage for this additional interlock mechanism includes a connecting rod 16 of hexagonal cross section. Rod 16 is pivotally connected at its lower end to the right end of lever 10 by a clevis 17. A stud 18 is welded to the bight of clevis 17 and is threaded into the lower end of rod 16 to provide an adjustable connection. By disconnecting and rotating clevis 17 the effective length of the connection may be adjusted by turning stud 18 into or out of the threaded end of rod 16. Clevis 17 is pivotally connected to lever by a pin 19 passing there through. The upper end of rod 16 is welded to a plate 20 which is best shown in FIG. 6. A pair of transversely elongated holes 21a and 21b are formed in plate 20.

A lever assembly 22 is fastened adjacent the lower end of contactor 6 to a vertical partition 23 in enclosure 2. Assembly 22 comprises a group of three levers 24, 25 and 26 pivotally supported on a mounting frame consisting of two spaced apart angle brackets 27 and 28 welded to a plate 29.

Lever 24 consists of a roughly triangular shape with a boss 30 welded to one side near one corner. A shaft 31 passes through brackets 27 and 28 and loosely through an aperture in boss 30 and lever 24 to provide pivotal support for lever 24. A pair of tubular spacers 32 and 33 are arranged on opposite sides of lever 24 on shaft 31 to properly aline lever 24 in the mechanism. Washers 34 and 35 and cotter pins 36 and 37 serve to retain shaft 31 in place. Pins 38 and 39 are securely fastened to the other two corners of lever 24 and extend to one side of lever 24. Pin 39 fits slidingly within hole 21b to provide a mechanical connection between lever 24 and plate 20. A washer 40 and cotter pin 41 secures pin 39 within hole 21b.

Lever 25 has at its lower end a slot 42 which silding- 1y fits over pin 38 and is secured thereon by washer 43 and a cotter pin 44. At its upper end lever 25 has a hook-like portion 45 having a lower edge 46 and a lateral edge 47. Lever 25 is pivotally mounted on shaft 48 which passes through lever 25 and a boss 49 which is welded to lever 25. Thus, the lever system including levers 24 and 25 is arranged so that when connecting rod 16 moves upwardly, hook-like portion 45 moves away from partition 23 into engagement with or into the path of projection 9.

Lever 26 is also pivoted upon shaft 48 which passes through lever 26 and a boss 50 attached to lever 26. Shaft 48 passes through apertures in brackets 27 and 28 and is secured by washers 51 and 52 and cotter pins 53 and 54. At its upper end, lever 26 has a hook-like member 55 similar to that of lever 25. Member 55 has a lower edge 56 and a lateral edge 57. Lever 26 has a lateral extension 58 with an attached pin 59 which fits sildingly within hole 21a and is secured therein by washer 60 and cotter pin 61. This lever 26 is arranged so that when connecting rod 16 moves upwardly member 55 moves toward partition 23 or just oppositely to the movement of member 45.

Referring to FIG. 2, the contactors 4 and 5 are both shown to be in their open positions. Under these circumstances the interlock mechanism permits levers 25 and 26 to assume the position shown wherein projection 9 clears members 45 and 55 and therefore free to move upwardly to the position shown in FIG. 2. Consequently, dynamic braking contactor 6 is free to close. As long as dynamic braking contactor 6 remains closed, the engagement of edges 47 and 57 with prejection 9 will not permit either of members 45 or 55 to move to the right. As a result the linkage including connecting rod 16 prevents lever 10 from tilting in either direction from the position shown in FIG. 2. Consequently, under these circumstances neither of contactors 4 or 5 may close.

When contactor 6 is open as shown in FIGS. 1 and 3, levers 25 and 26 are unrestrained and lever 10 may tilt either to the right as shown in FLIG- 3, in which position contactor 4 may be closed or to the left as shown in FIG. 1, in which position contactor 5 may close. When contactor 4 closes as shown in FIG. 3, the linkage including connecting rod 16 moves member 55 to the right in which position lower edge 56 restrains the upward movement of projection 9 to prevent closure of contactor 6.

When contactor 5 closes lever 10 tilts to the left and through lever 24 causes hook-like member 45 to move to the right where lower edge 46 blocks the upward movement of projection 9. Closure of dynamic braking contactor 6 is thereby prevented when contactor 5 is closed.

We claim:

1. An interlocking mechanism for an electrical controller including first, second and third contactors, each having open and closed positions comprising:

first interlocking means having a first position which it assumes when said first and second contactors are both open, and eifective when held in said first position to block the closure of either of said first and second contactors, said first interlocking means being movable to a second position by closure of said first contactor to block closure of said second contactor and movable by closure of said second contactor to a third position to block closure of said first contactor;

second interlocking means for interlocking the operation of said third contactor with said first and second contactors comprising:

first and second pivoted levers mechanically linked to pivot in opposite directions,

connecting means for connecting said first and second levers to said first interlocking means,

said first lever being movable to block closure of said third contactor when said first contactor closes,

said second lever being movable to block closure of said third contactor when said second contactor closes, and

means on said third contactor movable by closure of said third contactor for blocking movement of said first and second levers to thereby hold said first interlocking means in its first position to prevent closure of either of said first and second contactors.

2. The invention as defined in claim 1, in which said second interlocking means comprises in addition to said first and second levers:

a third pivoted lever connected to said second lever to cause said first and second levers to pivot in opposite directions; and

said connecting means comprises a single connecting rod linking said first and third levers to said first interlocking means.

3. The invention as defined in claim 2, in which said first interlocking means comprises a pivoted lever between said first and second contactors.

4. The invention as defined in claim 3, in which:

said first contactor is a forward motor contactor;

said second contactor is a reverse motor contactor; and

said third contactor is a dynamic braking contactor.

References Cited UNITED STATES PATENTS 2,3 81,243 8/ 1945 Armstrong 20050.3 2,780,685 2/1957 Sprow 200-503 2,904,649 9/1959 Ranson 200-50.3

ROBERT K. SCHAEFEiR, Primary Examiner. R. A. VANDERHY E, Assistant Examiner.

US. Cl. X.R. 7496, 104, 483 

